1. Field of the Invention
This invention relates to hydroformylation reactions wherein an olefin is reacted with carbon monoxide and hydrogen to form the corresponding saturated aldehyde.
2. Description of the Prior Art
U.S. Pat. No. 3,733,362 discloses a hydroformylation reaction wherein an olefin is reacted with carbon monoxide and an alcohol, amine, water or hydrogen in the presence of a catalyst of rhodium complexed with a biphyllic phosphorus ligand. High normal/iso (n/i) ratios of aldehyde, e.g. 8:1 are shown.
U.S. Pat. Nos. 3,946,082 and 3,939,188 disclose processes for hydroformylating olefins to produce aldehydes with high ratios of normal to iso. Zerovalent rhodium-phosphine catalyst complexes of the formula [L.sub.2 Rh].sub.2 where L is a bidentate ligand are used. The disadvantage of prior art rhodium-phosphine complexes was that they become sparingly soluble in the reaction mixture and required at least a 5-10 fold excess of phosphine.
U.S. Pat. No. 3,527,809 discloses a hydroformylation process for forming aldehydes with a high normal to iso ratio by using a rhodium-phosphine complex where the phosphine ligand is present in a molar ratio of 2-100:1. Typically, molar ratios of 55:1 and temperatures from 80.degree. to 100.degree. C. and pressures of 80 to 250 psia are used.
U.S. Pat. No. 3,981,925 discloses the use of platinum dichloride-polydentate phosphine-stannous chloride for use in the hydroformylation of alkyl olefins.
U.S. Pat. No. 3,168,553 discloses the use of a complex of rhodium and a phosphino or arsino ligand as a catalyst for the reaction of an olefin, carbon monoxide, and a reactant having an active hydrogen and an acid dissociation content not greater than 10.sup.-3, e.g. ethanol.